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The award-winning Phase Change Matters blog tracks the latest news and research on phase change materials and thermal energy storage. E-mail tips and comments to Ben Welter, communications director at Entropy Solutions. Follow the blog on Twitter at @PureTemp. Subscribe to the weekly PCM newsletter. Or join the discussion on LinkedIn.

Two Entropy advisors, Dr. Mohammed Farid and Lucas B. Hyman, are pleased to take your questions about PCMs and thermal energy storage. Send your questions to We'll select the best and post the answers here each week.




Patent application: Enclosure temperature control system

Ben Welter - Thursday, January 19, 2017

U.S. patent application 20170013789 (applicant Sustainable Energy & Agriculture Technology, Sahuarita, Ariz.):

SEAT patent application drawing"An enclosure temperature control system utilizes a renewable power source and a thermal sink to reduce the overall power requirements from a power grid. A renewable power source, such as a solar panel may provide power that drives the components required to maintain the greenhouse temperature within upper and lower limits, including a HVAC system and/or a heat transfer system coupled with a thermal sink. The thermal sink includes a phase change material that releases heat when it solidifies and this heat can be used to heat the greenhouse. Likewise, the phase change material absorbs heat during the day to reduce the temperature within the greenhouse. A heat transfer system may be coupled with the phase change material and a solid conductor component within the tank of a phase change material may increase thermal transfer rate."

Research roundup: Battery thermal management; plastic greenhouse thermal modeling; cementitious composites; more

Ben Welter - Wednesday, December 21, 2016

Investigation of phase change material based battery thermal management at cold temperature using lattice Boltzmann method [Energy Conversion and Management]

A study on thermal calculation method for a plastic greenhouse with solar energy storage and heating [Solar Energy]

Assessing the feasibility of integrating form-stable phase change material composites with cementitious composites and prevention of PCM leakage [Materials Letters]

Expanded graphite/disodium hydrogen phosphate/sodium acetate trihydrate stabilized composite phase change material for heat storage [pdf] [Journal of Thermal Science and Technology]

Coupling of solar reflective cool roofing solutions with sub-surface phase change materials (PCM) to avoid condensation and biological growth [Environmental Science and Sustainable Development]

Experimental Study on Thermal Performance Improvement of Envelop Integrated with Phase Change Material in Air-conditioned Room [International High Performance Buildings Conference]

U.S. patent: Rootzone heating for energy conservation using latent heat storage

Ben Welter - Monday, December 12, 2016

U.S. patent 9,510,515 (inventor Dr. William R. Sutterlin, Hoover, Ala; assignee Entropy Solutions LLC, Plymouth, Minn.):

U.S. patent image of root zone with micro PCMs"A plant pot or a plant container comprising: a phase change material (PCM) or a composition comprising a PCM, wherein the plant pot or plant container is formed from or has as part of its structure or has as a structural component comprising the PCM or composition comprising the PCM, and a sufficient amount of PCM is provided in or part of the plant pot or plant container to maintain a root zone environment having a consistent temperature environment or optimal temperature environment for a plant's root system growth or maintenance, and wherein the PCM or the composition comprising the PCM: (a) is positioned in as part of the plant pot or plant container to be approximate to, close to, in contact with, or substantially in contact with, the plant root system or a soil, or (b) is present as part of or as a structural component of the plant pot or plant container, in an amount sufficient to maintain a root zone environment having a consistent temperature environment or optimal temperature environment for the plant's root system growth or maintenance."

New wave of greenhouses use PCM to regulate temperature

Ben Welter - Monday, December 12, 2016

Traditional greenhouses are not all that green. Poor insulation and inefficient heating and cooling systems boost energy consumption and operating costs.

Colorado-based Ceres Greenhouse Solutions is among the growing number of companies offering commercial growers and backyard gardeners a better way. Ceres has designed and built hundreds of energy-efficient, year-round greenhouses since 2011. Key features include the use of free solar energy for both heating and cooling, improved insulation and phase change materials. Ceres says it is the first greenhouse company to integrate PCMs into its residential and commercial installations.

"We specialize in passive solar design — maximizing the use of solar energy for year-round heating," says Lindsey Schiller, director of marketing and business development. "These [greenhouses] use a combination of insulation and strategic placement of glazing (glass or plastics). The result is a more insulated and energy-efficient greenhouse capable of growing year-round in harsh climates with very little energy use. We also are well known for using a ground-to-air-heat exchanger we call the GAHTTM system, as well as integrating other sustainable / energy-efficient / renewable heating cooling systems."

Ceres greenhouse wall with PCM facingCeres uses film panels filled with phase change material to provide passive temperature control. The panels, sized to fit in a typical stud bay, help even out day-night temperature swings and reduce the need for active heating and cooling. The peak melting point of the PCM varies by climate.

"We usually recommend 60 F for cold-climate greenhouses with cold-tolerant crops where heating is needed, 80 F for hot-climate areas with heat-tolerant crops where cooling is the primary focus and 70 where both is desired," Schiller says. The panels are typically installed on the inner face of the north wall, as shown here.

The company originally used Phase Change Energy Solutions' BioPCM but recently switched to Insolcorp's Infinite R, a salt hydrate. Ceres sells the PCM for $3.50 a square foot. 

“One of the major things we have to think about is the durability of the packaging, particularly since it is exposed to direct light,” says Schiller. “We were concerned about the lifetime of BioPCM and switched to make sure we had a durable product that will hold up in a greenhouse environment.”

Another method for passive temperature regulation: fish tanks. Ceres recently announced a partnership with Colorado Aquaponics, a company that specializes in pre-fabricated aquaponic greenhouses. Ceres now offers kits that pair space-efficient aquaponic systems with highly efficient year-round greenhouses. Can PCMs play a role in these hybrid greenhouses?

"Yes," says Schiller, describing the technologies as complementary. "Greenhouses usually need several strategies to help control temperatures … not just one."

Research roundup: Polyethylene glycol/hydroxyapatite composite; root zone heating; lime plasters; more

Ben Welter - Tuesday, November 29, 2016

A polyethylene glycol/hydroxyapatite composite phase change material for thermal energy storage [Applied Thermal Engineering]

Phase diagrams, eutectic mass ratios and thermal energy storage properties of multiple fatty acid eutectics as novel solid-liquid phase change materials for storage and retrieval of thermal energy [Applied Thermal Engineering]

Analysis of the technical, environmental and economic potential of phase change materials (PCM) for root zone heating in Mediterranean greenhouses [Renewable Energy]

Effect of inclination angle on the melting process of phase change material [Case Studies in Thermal Engineering]

Densities of Selected Phase Change Materials in Liquid State [Chemical Data Collections]

Hygrothermal performance improvement of the Korean wood frame walls using macro-packed phase change materials [Applied Thermal Engineering]

Reinforcing and shape stabilizing of phase-change material via graphene oxide aerogel [Carbon]

PCM-enhanced Lime Plasters for Vernacular and Contemporary Architecture [Energy Procedia]

Characterisation and Enhancement of Phase Change Slurries [Energy Procedia]

Packed-bed Thermal Energy Storage Analysis: Quartzite and Palm-Oil Performance [Energy Procedia]

Thermal properties and reliability of eutectic mixture of stearic acid-acetamide as phase change material for latent heat storage [Journal of Chemical Thermodynamics]

Application of material assessment methodology in latent heat thermal energy storage for waste heat recovery [Applied Energy]

Research roundup: Heat storage system in diesel engine; integrating PCM in furniture; hybrid cooling vest; more

Ben Welter - Friday, November 18, 2016

Experimental study on heat storage system using phase-change material in a diesel engine [Energy]

Recycling Rhizopus oryzae resting cells as biocatalyst to prepare near eutectic palmitic-stearic acid mixtures from non-edible fat [Journal of Molecular Catalysis B: Enzymatic]

Dynamic thermal characteristics analysis of microencapsulated phase change suspensions flowing through rectangular mini-channels for thermal energy storage [Energy and Buildings]

Influence of internal thermal mass on the indoor thermal dynamics and integration of phase change materials in furniture for building energy storage: A review [Renewable and Sustainable Energy Reviews]

Experimental study of the thermal characteristics of microencapsulated phase change composite cylinders [Applied Thermal Engineering]

Experimental Investigation of Melting Behavior of PCM by Using Coil Heat Source inside Cylindrical Container  [Journal of Electrical Systems and Information Technology]

Simulation Study of Anomalous Thermal Properties of Molten Nitrate salt [Powder Technology]

Enhance heat transfer for phase-change materials in triplex tube heat exchanger with selected arrangements of fins [Applied Thermal Engineering]

Experiments on Thermal Performance of Erythritol/Expanded Graphite in a Direct Contact Thermal Energy Storage Container [Applied Thermal Engineering]

Hybrid cooling vest for cooling between exercise bouts in the heat: effects and practical considerations [Journal of Thermal Biology]

Research roundup No. 200: Rice-husk-char encapsulation; microsuspension iodine transfer polymerization; more

Ben Welter - Tuesday, August 30, 2016

Welcome to the 200th issue of the Phase Change Matters research roundup!

Encapsulation of phase change materials using rice-husk-char [Applied Energy]

Performance study of an enhanced solar greenhouse combined with the phase change material using genetic algorithm optimization method [Applied Thermal Engineering]

Innovative synthesis of high performance poly(methyl methacrylate) microcapsules with encapsulated heat storage material by microsuspension iodine transfer polymerization [Solar Energy Materials and Solar Cells]

Fabrication and characterization of a new enhanced hybrid shell microPCM for thermal energy storage [Energy Conversion and Management]

Experimental evaluation of thermal properties of r134a clathrates based PCMs for cooling applications [International Journal of Refrigeration]

Patent application: Greenhouse roofing having temperature-dependent radiation transparency

Ben Welter - Monday, August 08, 2016

U.S. patent application 20160219796 (applicant Tropotherm SL, Retamar, Spain):

Greenhouse patent application drawing"In plant cultivation, it is common in many cases to grow certain crops under film covers, in greenhouses, or under other roofings. Depending on the climate zone and crop, this can be used for example to supply heat by retaining the sunlight or by means of additional heating. The invention relates to a plant cultivation roofing made of film material or plate material having temperature-dependent radiation transparency, wherein a plastic layer in or on a plate or at least one film layer having temperature-dependent radiation transparency provides a gradual or a two-step or multi-step transparency reduction for rising temperatures in a temperature range from 20° C."

PCM briefing: EU research focuses on energy retrofits; Axiom Exergy raises $2.5 million

Ben Welter - Tuesday, August 02, 2016

• A European Union research project focused on retrofitting old buildings to meet EU efficiency standards is taking a close look at PCMs built into walls. “By using a phase change material which freezes at 18°C and melts at 25°C,” says Dr. Jürgen Frick, project coordinator, “we can regulate the temperature fluctuations of a room. If the temperature falls to 18°C, the PCM freezes and heats the room. When it rises to 25°, the PCM melts, energy is absorbed, and the room is cooled.”

Rally by Diamond Mattress• The latest entry in the bed-in-a-box mattress competition features open-cell foam infused with copper gel and phase change material to regulate temperature. Diamond Mattress of Rancho Dominguez, Calif., says the company's new Rally line will be sold online and in retail stores.

Eric Buchanan of the West Central Research and Outreach Center in Morris, Minn., has posted an update on his net-zero dairy project. The system's key components so far include solar thermal panels, a heat pump, three heat exchangers and a 2,000-gallon water tank. Fifty-four kilowatts of solar PV and two 10-kW wind turbines are now being added to the system.

Axiom Exergy has raised $2.5 million from investors to help bring its refrigeration battery to supermarkets and cold storage facilities across the United States. The system uses a salt-based phase change material to reduce peak power usage by up to 40 percent and provide backup cooling during power outages.

• The University of Birmingham's Birmingham Centre for Energy Storage is setting up a joint lab on energy storage research with Global Energy Interconnection Research Institute Europe, an organization founded by China's state-run utility. The lab will focus on thermal and cryogenic energy storage systems and their application in energy networks.

• New from Accuray Research: "Global Advanced Phase Change Material (PCM) Market Analysis & Trends - Industry Forecast to 2025"

• A research team at Camosun College in Victoria, British Columbia, has selected PureTemp phase change material for use in a study of greenhouse thermal storage systems. "One of the engineering students is focusing on designing racks for the PCM bottles that will be specifically engineered to slow release and speed recharge of the bottles," writes Becky Mason, an instructor at Camosun who helped organize the research project. "This is intended to optimize use of PCM in off-grid greenhouses where electric fans are not used to circulate air around the PCM."

PCM briefing: Pelican BioThermal opens offices in South Korea, Germany; BASF tops global list of chemical companies

Ben Welter - Friday, July 29, 2016

• Commercial appliance maker Rockwell Industries of Hyderabad plans to open a network of retail stores across India. Rockwell's products include a line of eutectic freezers designed to retain subzero temperatures for up to 16 hours in the event of a power loss.

• In partnership with CoolPack.comCold Chain Technologies of Holliston, Mass., is conducting an industrywide survey "to benchmark the methods used to maintain the efficacy of temperature sensitive therapeutics throughout the supply chain." Survey results will be published in October.

BASF, with chemical sales of $ $63.7 billion in 2015, is No. 1 on C&EN's latest Global Top 50 list. The magazine reports that the 50 companies combined for $775.2 billion in sales last year, a 10.8 percent decline from a year earlier.

Pelican BioThermal, the temperature-controlled packaging specialist, has added offices in South Korea and Germany to support growth in Asia and Europe.

Daniel Frey, a professor of mechanical engineering at MIT, has been appointed the new faculty director of the school's D-Lab. D-Lab's mission is to give students a hands-on opportunity to design and share affordable and effective technologies to address problems in developing countries. A PCM-powered vaccine cooler is among the projects Frey has worked on with students.

• New from Market Research FutureSoy-Based Chemicals Market Research Report Forecast to 2027

• New from QY ResearchGlobal Green Building Materials Industry 2016 Market Research Report

• New from Future Market InsightsTemperature Controlled Packaging Solutions Market: Global Industry Analysis and Opportunity Assessment 2015-2025

• Membership in ASHRAE has topped 56,000, the highest number in 14 years. The international organization focuses on energy efficiency, air quality, refrigeration and sustainability in the built environment. It has members in 130 countries.

• A group representing manufacturers of refrigeration and air conditioning equipment is pushing the European Union to set tougher energy-efficiency targets. The European Alliance to Save Energy argues that doubling the EU’s current annual rate of energy productivity of around 1.5 percent would sharply reduce household energy bills, increase GDP and create more than a million jobs.